An inflatable vehicle occupant protection device, such as an air bag, is deployed upon the occurrence of a vehicle collision. The air bag is part of a conventional vehicle occupant protection apparatus that includes a collision sensor and an inflator. The inflator includes a housing and an inflation fluid source in the housing. Upon sensing the occurrence of an event for which inflation of the air bag is desired, the inflator is actuated and produces inflation fluid under pressure in the inflator housing. The pressurized inflation fluid is directed out of the inflator housing and inflates the air bag into the vehicle occupant compartment to help protect the vehicle occupants.
When the inflator is actuated at an elevated ambient temperature, the pressure of the inflation fluid in the inflator housing increases. An inflator must be strong enough structurally to contain these elevated pressures. If the pressure in the inflator housing is increased in this manner, the mass flow rate of the inflation fluid flowing into the air bag may also increase.